It is said that combined energy consumed by a gas compressor of an air compressor or the like corresponds to 20 through 25% of an energy consumed by a total of a plant and an effect of recovering waste-heat from the gas compressor is significant. Particularly, it is anticipated that utilization of waste-heat from a gas compressor is going to be regarded to be more and more important in the future also for achieving a target of reducing a CO2 emission amount originated from the global warming problem.
A gas compressor is configured by a compressor main body for compressing gas of air or the like, a cooling system for absorbing heat generated by a compressive operation, a motor which is a driving power source of the compressor and the like. Further, in a gas compressor, when motor input power is regarded as 100%, an amount of heat absorbed in the cooling system corresponds to 90% or more of the motor input power, the amount of heat is ordinarily emitted to external air, and a very large amount of energy is emitted to the atmosphere. Although high efficiency formation of the compressor main body or the motor is promoted for reducing the emitted heat amount, its effect is limited to several %, and it is requested to effectively utilize the waste-heat from the gas compressor.
With regard to effective utilization of the waste-heat from the gas compressor, there are cases of utilization for heating, utilization for hot water, utilization for preheating of water fed to a boiler and the like.
Incidentally, there are background arts of this kind described in Japanese Patent No. 4329875 (Patent Literature 1) and Japanese Unexamined Patent Application Publication No. 2012-67743 (Patent Literature 2).
According to the background art described in Patent Literature 1, a compressor is driven by using steam, and consumption energy of a boiler is reduced by utilizing heat generated at the compressor for preheating water (feed water) supplied to the boiler.
According to the background art of Patent Literature 2, a waste-heat-recovery heat exchanger is provided to an oil-cooled gas compressor, and waste-heat from oil or the like heated by cooling the compressor is enabled to recover.